1. Field of Invention
The present invention relates to an apparatus for forming a nano-grating device, and more particularly to an apparatus for forming a nano-grating device by retrieving nano-scale interference fringes using a holography process.
2. Related Art
A holography is based on the visual effect generated by optical interference and diffraction. In practice, two highly coherent beams (usually, laser beams) are used to interfere with each other to form a plurality of interference fringes that are then recorded on a photosensitive material and then developed.
In recent years, the holography has been widely used in various fields such as Display Holography which provides 3-D images, holographic data access, holographic cameras, and the formation of grating devices and so on. By means of imposing the grating devices with different angles, a filter that can filter and save particles can be made.
A cause of Serious Acute Respiratory Symptom (SARS) that has swept across the world and has become a statutory infectious disease is a deformed coronavirus that spreads over through breathing in flying particles of the saliva or phlegm of a sick person. Therefore, people can effectively avoid SARS by avoiding any contact with spatters or mists spray of the sick person.
Therefore, the people or doctors and nurses who often contact the sick persons need to wear masks to filter virus, bacteria or dust particles to prevent the infection of SARS.
However, the currently available active carbon masks can filter large-molecule dusts, viruses, toxic gases and peculiar smells, but small-molecule (30 nanometers–300 nanometers) viruses cannot be filtered.
In fact, professional medical N-95 masks only filter 95% fine particles (300 nanometers–90 nanometers). The coronavirus and paramyxovirus (100 nanometers–300 nanometers), and SARS virus (80 nanometers–160 nanometers) cannot be completely filtered.
For the application of the holography in taking grating images, the grating cycle cannot be below 100 nanometers due to the limitation of the laser (i.e., the diffraction limitation restricts the grating cycle to be higher than half of a light wave of the laser).
Therefore, there is a need of a filtering structure for making a mask that can filter viruses and bacteria to protect the people from being infected.